Hydraulic valve lifters for internal combustion engines are well known. Some prior art lifters are specially constructed to permit selective deactivation of an engine valve as desired, thereby selectively deactivating the corresponding engine cylinder; see, for example, U.S. Pat. No. 6,497,207 B2, issued Dec. 24, 2002 to Spath et al., the relevant disclosure of which is herein incorporated by reference.
A typical prior art deactivation lifter includes an elongate lifter body having a lower end configured for engaging a cam of an engine. An elongate pin housing slidably disposed within the lifter body includes a radially directed pin bore. A plunger is concentrically disposed within the pin housing. A deactivation pin assembly is disposed within the pin bore and includes two pin members that are biased radially outward relative to each other by a spring therebetween to selectively couple the pin housing to the lifter body when valve activation is desired. The pin members are configured for moving toward each other when the pin chamber is pressurized, thereby retracting the pin members from within the lifter body and decoupling the lifter body from the pin housing when valve deactivation is desired. An elongate spring tower for retaining a lost motion spring has an outer wall concentrically disposed and retained within the outer end of the pin housing. The spring tower typically has slotted tabs or other engagement means and is flexible enough to be pushed downward into the pin housing during assembly until each of the tabs is received within and snaps into or otherwise engages an upper annular groove formed in the inside wall of the pin housing, or into an expansion ring disposable into the annular groove.
The assembly procedure requires that many steps be performed correctly to produce a usable pin housing and spring tower sub-assembly. The procedure is subject to error, however, in that the length of the plunger return spring is less than the diameter of the receiving well in the pin housing, such that the spring may inadvertently and catastrophically turn sideways in the pin housing prior to installation of the plunger sub-assembly against the spring rendering the lifter inoperative or adding significantly to the assembly time of the lifter.
Further, in lifter manufacture, it would be useful to have a pin housing sub-assembly that is self-contained and may be transported or tested or inventoried without falling apart.
Therefore, what is needed in the art is a pin housing sub-assembly wherein the plunger return spring cannot be mis-installed by turning sideways, and wherein the sub-assembly including an expansion ring is held together by the expansion ring itself.